Firmware Capstones

Interactive lab

This page is a live simulation rather than a written lesson: enable JavaScript to use its controls, visualizations, and code traces. The written lessons for this subject are linked below.

More in Embedded DSA

• The WorkbenchA complete embedded-first DSA course with theory, 80 challenges, complete C11 implementations, visual traces, mastery tracking, interview drills, and a constraint-driven firmware design arena.
• Arrays & WindowsTwo pointers, sliding windows, in-place compaction and streaming filters over sample buffers. Twelve problems with complete C11 solutions, complexity targets and edge-case tests.
• Search & LookupBinary search that actually terminates, lookup tables, perfect hashing and command dispatch. Eleven problems on getting a bounded answer out of a table without a heap allocation in sight.
• Lists, Pools & ArenasIntrusive linked lists, fixed-block pools, arena allocators and why malloc is banned in most firmware. Ten problems on owning memory with a bound you can prove before the board ships.
• Trees, Graphs & StateTries for command tables, union-find for connectivity, and state machines that cannot reach an undefined state. Nine problems on structures that encode relationships rather than sequences.
• Parsing & ProtocolsFraming, COBS, incremental parsers and adversarial input. Nine problems on decoding a byte stream from a hostile world without a buffer overflow or an unbounded loop.
• Linked ListsEvery list variant, written for embedded C rather than for a whiteboard: singly and doubly linked, circular lists and sentinels that delete the boundary cases, the intrusive form kernels and firmware actually use, static pools and free lists for systems without malloc, reversal and cycle detection, and an honest account of when an array is the better answer.
• Sorting Under ConstraintWhich sort survives a 512-byte stack and a fixed deadline. Insertion sort for small nearly-sorted windows, heapsort when the worst case must be provable, counting sort for byte keys, and a bounded-depth quicksort - six problems with complete C11 solutions.
• Heaps & SchedulingBinary heaps as timer wheels and task schedulers, and wrap-safe time comparison - the bug that only shows up 49 days after the board is deployed. Eight problems with complete solutions.
• Integer & Fixed-Point MathComputing the right number with no floating-point unit. Q formats, multiply-before-divide, rounding instead of truncating, division by a constant as a multiply and shift, running averages that do not stall, and LFSR jitter for backoff.
• Stacks, Queues & RingsThe ring buffer and the SPSC queue: the two structures every firmware project actually ships. Ownership between an ISR and a main loop, overflow policy, and why the full/empty test is where the bugs are.
• Bits & BytesRegister fields, bit reversal, parity, endianness and portable packet decoding, without invoking undefined behaviour. Seven problems with complete C11 solutions and a step-by-step trace for each.